The peak differentiation of the spermathecal accessory gland of mealworms occurs during the pupal instar and over the first week of adult life. Ultrastructural and electrophoretic indices for scoring the differentiation will be improved. The patterns of ribosomal and messenger RNA synthesis will be analyzed in the known context of phenotypic change. The glands will be cultured in vivo (transplantation) and in vitro (Landureau's medium) and hormones will be added to the culture media. We intend to pinpoint those changes in competence which are hormonally dependent and those transitions in phenotype which are also hormonally dependent.